The beer will now contain only five natural ingredients - water, malted grains, yeast, cane sugar and hops, in what the brewer has described as a "back to basics" approach.

The iconic Queensland lagers are among a number being changed under a campaign by drinks conglomerate and owner of the Milton Castlemaine Perkins XXXX brewery, Lion Nathan.

NSW beers Tooheys New and Tooheys Old, South Australian brew West End Draught and Western Australian icon Swan Draught are also shedding their additives.

The beers - including the XXXX duo - will be given new packaging and carry a stamp that reads, "Natural beer promise: brewed in compliance".

Lion Nathan chief brewer Bill Taylor yesterday said caramel would no longer be used to even out colour inconsistencies, and preservatives - which had been used to extend beer's shelf life - would be dropped.

New technology allows breweries to suck the oxygen out of beer bottles and top them with carbon dioxide before capping them. Preserving enzymes had also been given the chop, Mr Taylor said.

Fourex beer made under the new process is expected to begin leaving Castlemaine Brewery on October 1 and be in stores and pubs across Queensland by mid-month.

Mr Taylor said Australians had become increasingly conscious of what they consumed.

A Lion Nathan survey of more than 1000 beer drinkers this month showed nine out of 10 were also unsure what ingredients were used to make beer.

"There is a growing interest in all things natural right across food and beverages and we found that if people had the option for a natural beer that is the option they will choose," he said.

"The taste, quality and appearance of these beers haven't changed. We've simply taken out some additives, improved the way we do things, and gone back to the basics of brewing with only five natural ingredients."

Matt Kirkegaard, editor of Beer and Brewer magazine, said he was not surprised by Lion Nathan's new approach, with Australian drinkers increasingly turning to boutique beers.

"These big brewers are in business and their aim is to sell as much beer as they can so if people want preservative-free products it is not surprising they have done that," he said.

"This is one of those of those examples where consumer demand has forced the hand of the bigger players."

He said many beer drinkers also believed preservatives in beer were linked to more severe hangovers.

"In my experience I have been better after drinking the more natural German beers generally than some beers with preservatives in them - but the secret is to drink in moderation."